Bleaching compositions are well-known in the art. Amongst the different bleaching compositions available, those relying on bleaching by hypohalite bleaches such as hypochlorite are often preferred, mainly for performance reasons, especially at lower temperature.
However, a problem encountered with the use of hypochlorite based-compositions is the resulting damage and/or yellowing of the fabrics being bleached.
It is therefore an object of the invention to provide a hypohalite-containing composition, suitable for use in laundry applications, which provides improved fabric whiteness to fabrics treated therewith.
It is another object of the invention to provide a hypohalite-containing composition, suitable for use in laundry applications, which provides improved fabric safety to fabrics treated therewith.
The Applicant has thus now surprisingly found that this problem is solved by the provision, in a hypohallite bleaching composition, of a phosphate ingredient. Indeed, it has been found that improved fabric whiteness and/or safety were obtained with the composition of the invention compared to hypohalite compositions without said phosphate ingredient. The benefits are particularly noticeable in hypohalite bleaching compositions which further comprise a pH buffering component.
Another advantage of the compositions of the invention is that they are chemically stable. By "chemically stable", it is meant that the hypohalite bleaching compositions of the present invention should not undergo more than 15% loss of available chlorine after 5 days of storage at 50.degree. C. .+-.0.5.degree. C. The % loss of available chlorine may be measured using the method described, for instance, in "Analyses des Eaux et Extraits de Javel" by "La chambre syndicate nationale de L'eau de Javel et des produits connexes", pages 9-10 (1984). Said method consists in measuring the available chlorine in the fresh compositions, i.e. just after they are made, and in the same compositions after 5 days at 50.degree. C.
A further advantage of the compositions of the invention is that they are suitable for the bleaching of different types of fabrics including natural fabrics (e.g., fabrics made of cofton, viscose, linen, silk and wool), synthetic fabrics such as those made of polymeric fibers of synthetic origin as well as those made of both natural and synthetic fibers. Indeed, the compositions of the present invention may be used on synthetic fibers despite a standing prejudice against the use of hypohalite bleaches, especially hypochlorite bleaches, on synthetic fibers, as evidenced by warning on labels of commercially available hypochlorite bleaches and clothes.
EP 0 188 145 discloses bleaching compositions comprising trisodium phosphate. J53081789 discloses compositions comprising hypochlorite and a phosphate ingredient for the cleaning of carpets. J03137278 discloses a composition comprising hypochlorite and a phosphate ingredient for the bleaching of indigo-dyed cloth. J08081878 discloses bleaching compositions with a phosphate ingredient for the bleaching of raw textiles. None of these prior art documents discloses the fabric whiteness and safety benefits obtained from the provision of a phosphate ingredient in a hypochlorite composition.